1. Field of the Invention
The present invention relates generally to power saving modes for electrical devices, and more particularly, to power saving modes for cable modem systems.
2. Description of Related Art
In cable modem systems, a cable modem termination system (CMTS) at one end of a cable network typically services multiple cable modems (CMs) connected to the cable network. CMs are generally installed locally at the end-user's location, and communicate with the CMTS, which may be installed at a cable company's facility. Lately, there has been interest in operating CMs as Multimedia Terminal Adapters (MTAs) by running a Voice over IP (VoIP) application on the CMs. The voice service provided by such a CM/MTA may be considered a “primary line” service. In other words, the voice service provided by the CM/MTA may be the primary way a user connects to other people and/or emergency services via the public switched telephone network (PSTN).
In the event of power loss, it is desirable for the user of the CM/MTA still to be able to originate calls, receive calls, be notified of incoming calls (e.g., by ringing), and so on. During such power loss, the CM/MTA may still receive power from an internal power source or uninterruptible power supply (UPS). To avoid excessive drain on the UPS, and to draw lower average power in general, it may be desirable for the CM/MTA to operate in a low power mode (i.e., a “power saving” mode).
For example, it may be desirable for the CM/MTA to operate in a low power mode during periods of non-use, so that the long-term, average power consumption of the device is less than about 3 Watts. Further, low power operation of one CM should not adversely affect operation of other CMs served by the same CMTS. The current Data over Cable Service Interface Specification (DOCSIS) protocols (e.g., DOCSIS 1.1, 2.0), however, contain no provision for operating CMs in a low power mode.
Therefore, there exists a need to reduce power consumption of CMs in cable modem systems.